1. Field of the Invention
The present invention relates to an adjustable parallax barrier 3D display, and more particularly, to an adjustable parallax barrier 3D display.
2. Description of the Prior Art
Generally speaking, an image seen by the left eye of the observer is quite different than an image seen by the right eye of the observer, where the image seen by the left eye is often referred as a left view or a left-eye image, and the image seen by the right eye is often referred as a right view or a right-eye image. In the current technology trend, 3D Video display devices are wildly used. Taking stereoscopic display for example, there are Red-Cyan anaglyph glasses, liquid crystal display shutter (LCD-shutter) glasses, and a micro retarder with polarized glasses.
A display cooperating with LCD-shutter glasses displays a left-eye image and a right-eye image within a tiny time-frame, where the left-eye image is retrieved from various viewpoints of the left eye, and the right-eye image is retrieved from various viewpoints of the right-eye. Then the LCD-shutter glasses hinders the left-eye image from being seen by the right eye of the observer, and hinders the right-eye image from being seen by the left eye of the observer. The LCD-shutter glasses make use of visual persistence by displaying an amount of images having lots of right-eye images and left-eye images within a tiny time, and the stereo vision of the observer is thereby generated by alternatively displaying left-eye images and right-eye images in turn rapidly. A micro-retarder with polarized glasses filters images having different poles so that extreme images are observed. For example, an extreme left-eye image is observed by the left eye of the observer without being interleaved with right-eye images, and an extreme right-eye image is observed by the right eye of the observer without being interleaved with left-eye images. Red-Cyan anaglyph glasses use glasses of different colors for filtering off specific colors, and combines images filtered off the specific colors again for generating the stereo vision for the observer.
There are some 3D video display devices other than glasses that are utilized for generating stereo vision, such as a two-view 3D-LCD and a multi-view 3D LCD. A two-view 3D-LCD simply makes use of left-eye images and right-eye images.
Please refer to FIG. 1, which is a diagram for illustrating basics of parallax barriers used on an LCD display. A location 102 indicates where a left eye of an observer stays, and a location 104 indicates where a right eye of the observer stays. Both left-eye images 106 and right-eye images 108 are displayed on a display. Parallax barriers 110 are disposed between the locations 102 and 104 and the images 106 and 108 for refracting lights emitted from the images 106 and 108. With the aid of refraction generated from a parallax barrier 110, as shown in FIG. 1, lights emitted from a left-eye image 106 is hindered by the parallax barrier 110 from reaching the location 104, and lights emitted from a right-eye image 108 is hindered by the parallax barrier 110 from reaching the location 102. Therefore, stereo vision may thus be observed by the observer. According to descriptions in FIG. 1, sweet spot for locating eyes of the observer are pre-defined. However, the stereo vision cannot be observed by the observer when eyes of the observer move away from the defined sweet spots.
Please refer to FIG. 2, which is a schematic diagram for illustrating sweet spots according to FIG. 1. As shown in FIG. 2, an extent of a left eye feasible region, which corresponds to the location 102 shown in FIG. 1, indicates the fact that when the left eye of the observer stays within said region, the left eye observes merely left-eye images on the LCD display. Similarly, an extent of a right eye feasible region, which corresponds to the location 104 shown in FIG. 1, indicates the fact that when the right eye of the observer stays within said region, the right eye observes merely right-eye images on the LCD display. The abovementioned sweet spots lie in the extents of the left eye feasible region and the right eye feasible region, and also the extents of the sweet spots distance from the LCD display with a predetermined viewing distance d, which is also illustrated in FIG. 2. However, when eyes of the observer leave extents of the sweet spots, no stereo vision is observed by the observer. Therefore, every time when activating the LCD display, the observer has to find the sweet spots again, making it inconvenient to the observer. Moreover, even if the sweet spots are found, the observer still has to ensure that his or her eyes stay at the sweet spots, and it is cumbersome for the observer.